Process of copper base product within iron base can



Oct, 28, 1969 w. l.. F|NLAY ETAL. 3,474,516

PROCESS 0F COPPER BASE PRODUCT WITHIN IRON BASE CAN Filed Jan. 24, 19672 Sheets-Sheet l \\\\`v\:i2 l l E" 2 C lNVENTORS BY 'paw/4.

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ATTORNEYS Oct. 248, 1969 w, FINLAY ETAL 3,474,516

' PRocass or 'COPPER BASE: PRODUCT WITHIN IRON BASE CAN Filed `Ian. 24.1967 2 Sheets-Sheet 2 'FIG.6

M- lNVNTORS BY WMM?,-

^ ATTORQNLEYS United States Patent O 3,474,516 PROCESS OF COPPER BASEPRODUCT WITHIN IRON BASE CAN Walter L. Finlay, New York, N.Y., andDonald A. Hay, Medford, and Wendell T. Hess, Acton, Mass., assignors toCopper Range Company, New York, N.Y.,I a corporation of Michigan FiledJan. 24, 1967,I Ser. No. 611,294

Int. Cl. B23p I 7/ 02 U.S. Cl. 29--423 v 27 Claims ABSTRACT OF THEDISCLOSURE stratum. Thus copper and iron-constitute a synergistic pairin connection with the contemplated can processes and products.

BACKGROUND OF THE INVENTION The present invention relates to theprocessing of copper metals, i.e. copper and copper alloys, and, moreparticularly, to the conditioning and working of copper metals followingconverting.

Generally, extraction of copper from an ore such as chalcopyrite (whichcontains the copper primarily as the sulfide) involves: milling the oreto line particle size; froth flotation by which copper rich particles inan aqueous suspension adhere to gas bubbles that rise to the surface ofthe suspension where the copper rich particles are collected andconcentrated; roasting the concentrate to eliminate water and to oxidizesome of the sulfur; smelting to eliminate unwanted residues as slag andto separate the copper therefrom in the form of cuprous sulde; andconverting the cuprous sulfide to metallic copper by oxidizing thesulfur to sulfur dioxide,

which becomes separated as a gas. Since sulfur, even in very smallconcentrations, in copper tends to increase brittleness and reduceconductivity, it must lbe removed completely with the aid of a slightexcess of oxygen. The result is copper oxide formation. Oxygen, thoughnot to the same degree as sulfur, tends to have a similar effect but hasbeen relatively expensive to remove and control. The present inventionis concerned withy the removal or control of such oxygen, and withcertain products made feasible thereby.

SUMMARY OF THE DISCLOSURE The primary object of the present invention isto provide processes for and products of the removal or control ofoxygen from a copper metal composition ofthe foregoing type, in thefollowing manner. The copper metal composition, including any desirednon-,copper components, is enclosed within a close fitting can, i.e.casing. The can characteristically contains iron and is capable ofgettering oxygen from the copper metal composition, on heating, in orderto render it or optionally its surface oxygen free.v The copper metalcomposition may be mechanically Worked while in the can in such a waythat, despite deformation of the can along with its contents, removal ofthe can from its contents at the end of ice the process is notdifficult. In accordance with the present invention, therefor, copperand iron constitute a synergistic pair. i

Other objects of the present invention will in part be obvious and willin part appear hereinafter.

For a fuller understanding of the nature and objects of the presentinvention, references is to be had to the accompanying drawing wherein:

FIG. l is a schematic ow diagram illustrating copper deoxidation inaccordance with the present invention;

FIG. 2 is a schematic ow diagram illustrating clad -copper metalproduction in accordance with the present invention;

FIG. 3. is a schematic flow diagram illustrating copper powdercompacting and sintering in accordance with the present invention; l

FIG. 4 is a schematic flow diagram illustrating copper Winning andconsolidating in accordance with the present invention;

`FIG. 5 is a schematic ow diagram illustrating dispersoid strengtheningin accordance with the present invention; and

FIG. 6 is a schematic il'ow diagram illustrating slab consolidating andworking in accordance with the present invention.

SPECIFIC DISCLOSURE The processes described specifically hereinbelowincorporate a combination of two or more of the following steps, insofaras such steps are not inconsistent: (1) enclosing a metallic mass of acopper composition in a metallic can of an iron composition; and/or (2)predeterminedly heating the entire assemblage to a temperature at whichoxygen diffuses to the surface of the copper, oxygen is released fromthe surface of the copper, oxygen migrates to the surface of the ironand oxygen reacts with the iron to form a stable solid; and/or (3)heating the entire assemblage to a temperature at which some chemical orphysical change other than copper deoxidation occurs; and/or (4)mechanically working the entire assemblage with the can remainingsealed; and/ 0r (5) removing the can from its contents -by chemicallydissolving or mechanically stripping. Various examples of combinationsof these steps are given in the six examples below, which areillustrated in the six gures of ,the drawing.

Generally, the copper metals useful in accordance with .the presentinvention include commercial bulk and particulate copper and variouscopper alloys. Contemplated commercial bulk or particle copper,forexample typically includes the following.

(1) Electrolytic tough pitch (ETP) copper which contains by total weightin a remainder of copper: combined oxygen in the form of CuZO anddissolved oxygen- 0.04%; and nickel, iron, bismuth, arsenic-trace;

(2) Lake copper, which contains by total weight in a remainder ofcopper, from 0.05 to 0.089% silver, in addition to minor proportions ofoxygen, nickel, iron, bismuth and arsenic, as specified above inconnection with ETP copper;

(3) Oxygen free (OF) copper, containing by total weight in addition to aremainder of copper: iron- 0.0005 sulfur-0.0025%; silver-0.001%; nickel-0.0006%; tin-0.0002%; arsenic-0.0003%; selenium'- 0.0002%;tellurium-0.0001%; lead-0.0006%; antimanganeSe-0.0005 bismuth- 0.0001%;and oxygen-0.0002%.

When deoxidation is contemplated, the copper alloys are those containingcopper as their characteristic ingredient, preferably in excess of 50%by total weight, and

one or more other metals that are less active than iron, namely cadmium,cobalt, nickel, tin, lead, arsenic, rhenium and bismuth. These metalshave a lower negative free energy of oxide formation than iron. Thephysical form of the copper metal is either one or more solid cast cakesor ne particles. When deoxidation is to be avoided, other alloyingmetals may be employed.

Generally, the iron composition of the can is a low cost metal such asfollows. A typical wrought iron composition for the foregoing purpose,by total weight contains: carbon 0.02%; manganese 0.03%; phosphorus0.12%; sulfur 0.02%; silicon 0.15%; iron-remainder. A typical acidbessemer, mild steel for the foregoing purpose, by total weight,contains: carbon 0.07%; manganese 0.35%; phosphorus 0.10%; sulfur 0.05%;silicon 0.02%; and iron-remainder. A typical open hearth, mild steel forthe foregoing purposes by total weight, contains: carbon 0.10%;manganese 0.40%; phosphorus 0.03%; sulfur 0.03%; silicon 0.02%; andiron--rernainder- A typical stainless steel for the foregoing purpose,by total weight contains: nickel-18 chromium-8 carbon- 0.03%; andiron-remainder.

Preferably the thickness of the iron can, depending upon the size of theassemblage and upon the contents to be deoxidized, ranges from 1/s inchto one inch or more, a typical thickness being 1A inch.

Generally, oxygen removal from the copper composition within the can iseffected in a vacuum which is produced by exhausting the can through anopening to a pressure as low as conveniently possible, e.g. below 20 mm.Hg, preferably in the range of 0.1 to 1.0 micron mm. Hg, in order toreduce the demands on the gettering agent which is constituted either bythe iron can itself or by a large surface iron confgration in the can.After evacuation, the opening in the can is sealed and the can isheated, `together with its contents, to a temperature within theapproximate range 1400 to 1800 F. for the period necessary to effectdeoxidation to the degree and depth desired. The gettering process maybe enhanced either by a gaseous transfer agent or a solid large surfacedeoxidizing agent, the former of which may be introduced into the canfollowing evacuation of air and the latter of which may be introducedinto available space in the corners or at the edges of the can. Asuitable gaseous transfer agent is hydrogen, which may be utilized onlywhen not in too large a concentration, preferably when at a pressure ofless than 20 mm. Hg. The arrangement is such that the hydrogen reactswith the oxygen to form water Vapor not only with surface oxides butalso with copper oxides in the interior of the Cu. Water vapor formed onthe surface of the Cu migrates over to the Fe can or getter in the can,reacts with it to form stable iron oxide and hydrogen. Some of thelatter diffuses out through the Fe can and is lost; most, however,migrates back to deoxidize more Cu. Water vapor formed in the interiorof the Cu causes ssuring of the copper mass. However, if the copper massis retained within the can during hot rolling, the fissures are weldedtogether. Suitable solid gettering agents, such as finely divided ironpowder or steel wool, also, may be employed. The gettering procedure canbe continued either to a point at which the surface only of the copperis deoxidized or to a point at which the entire copper mass isdeoxidized.

Generally the copper composition contents of the iron composition canmay be worked advantageously without separation following deoxidation.The reason for this possibility is that iron is more or less inert tocopper, forming no intermetallic compounds therewith and havingrelatively low solid solubility therein. Thus, if the copper has anappreciable amount of oxygen, the iron will getter it to form brittleiron oxide at the interface, by which the iron later may be easilypeeled from the copper and by which solid state diffusion or iron intothe copper is blocked. If the copper has no appreciable concentration ofoxygen, the largely inert iron simply welds to the 4 copper surface andcan be removed by pickling, for example in sulfuric acid. Alternatively,in the latter case, .a release barrier may be interposed between theiron and the copper, for example, aluminum oxide powder, may beinterposed in order to establish a release interface.

If, as in the case of lake copper, iron oxide particles are present inthe copper mass, hydrogen should not be used. Rather i-ron should beused since it has been discovered that deoxidation by solid iron in avacuum outside the'copper mass will not affect iron oxide within themass. This is fortunate since if the iron oxide particles weredeoxidized, the iron, by virtue of its line size and intimacy with the"copper, would diffuse into the copper mass and thereby reduce theelectrical conductivity.

The following non-limiting examples further illustrate the presentinvention.

Example I--FIG. 1

In a typical process embodying the present invention, an as-cast,unconditioned Lake Copper cake is encased in a steel can 12, an opening14 being left in the jacket to permit evacuation. As shown inexaggerated fashion, the copper `cake has copper oxide imperfections at16, 18 and 20 and contains iron oxide grains at 21. The can is evacuatedthrough opening 14 to a pressure below about 1 mm. Hg, The opening thenis closed as by hammering or bending the pipe shut and welding itcompletely sealed before disconnecting the vacuum pump. Thereafter thecan, is heated to a temperature of approximately 1800 F. Thistemperature and pressure are maintained for a sucient period to enablecopper oxide to decompose into copper and oxygen and oxygen to migratethrough the void separating the copper cake and the steel can to formiron oxide at 22 and 24. Iron oxide particles 21 within the copper cakeare unaffected. Optionally this temperature and pressure are maintained`for a suicient period to enable the decomposition of copper oxideparticle 20, the diffusion of the resulting oxygen through the coppercake and the migration of oxygen to the steel can where iron oxide formsas tat 25. Thereafter, the copper cake, while within jacket 12 is hotrolled to form a steel-copper-steel sandwich at a temperature of 1600 F.Finally the steel jacket is removed by pickling in sulfuric acid.Thereafter further hot and cold rolling are effected to produce coppersheet as at 27.

Example II-FIG. 2

A slab of copper 30 is interposed between two slabs of cupronickel 32,34, the thicknesses of the three slabs bearing the relationship:cupronickel-15%; copper- 70%; cupronickel-15%. The total slab,approximately 8 inches thick, 2 feet wide and 10 feet long, is enclosedwithin a 1A inch thick mild steel can 36. The entire assemblage isheated to a temperature ranging from 1000 to 1400" F, while hydrogen ispassed throgh the can to reduce all the copper and nickel oxides. Theports 38, 40, which permit the passage of hydrogen through the can, thenare closed. The entire assemblage next is heated to =hot trollingtemperatures of from 1400 to 1800 F. and the entire assemblage is rolledto provide one monolithic met-allie blank 39. Next the entire assemblageis cold rolled to about 50% more than nal thickness. Then the steelsheath 41, 42 is removed by pickling in sulfuric acid. Finally thecupronickel-copper-cupronickel sandwich is cold rolled to ultimatethickness.

In an optional modication of the present example, the hydrogendeoxidation step is replaced by deoxidation by reaction with the iron ofthe can.

Example III-FIG. 3

Copper powder 44, approximately 325 mesh in particle size, is placed ina mild steel can 46 that is 10 feet long by 2 feet wide by 6 inches deepand 1A inch thick. The apparent density of the copper powder is about0.15 pound per cubic inch. Next the can is evacuated at room temperaturethrough a port (not shown) and the port is welded shut. The assemblageis heated to a temperature of 1600 to 1800 F. The base 48 of the cansupports a pair of thick mild steel blocks 50, 52 for a reason now tobecome apparent. As a result of the heating, the copper powder sinterstogether into a compact mass approximately l/2 its original volume.Since the inside of the can has been evacuated and since 1A: inch mildsteel at l600 F. is not very strong, the top of the can collapses as at54. Buckliug of the edges of the can is prevented -by blocks 50, 52. Thecombination of the box construction of the can and the sinteredcoherency of the copper powder permits hot rolling the can to athickness of about 1/2 inch. The steel sheath now is stripped from theresulting copper sheet and the copper sheet finally is cold rolled toits ultimate thickness.

Example IV-FIG. 4

The dimensions of the can used in the following win- -ning andconsolidation process are the same as were the dimensions in ExampleIII. Cu20 and Cu2S powders 60, 62 are mixed and placed in a mild steelcan in proportions that are stoichiometric with respect to the oxygenand sulfur. Heating at 1700 F. while evacuating is effected inaccordance with the formula:

Following evacuation of `all SO2 revolved, the port through which theS02 is evacuated is welded shut, Sintering, rolling and stripping thenare effected as in Example III.

Example V-FIG. 5

A dispersoid strengthened copper composition is produced in accordancewith the presen-t invention as follows. A can of the dimensionsspecified in Example III is filled with a mixture of copper and aluminumparticles. The copper particles contain just enough oxygen as oxides andin solid solution to react with all the aluminum metal in the aluminumpowder. Hence the inner surface of the can is rendered inert, as byoxidizing or coating with A1203, powder so its does not gather theoxygen. Next the can is evacuated and sealed. When the assemblage isheated to 1800 F., several reactions occur. C1120 decomposes to Cu and02. Al expands more than A1203 but any particles A1203 coating thatthereby cracks is promptly repaired by the 02 from the Cu20, wherebymolten Al is prevented from running onto the Cu. The Cu powder sinterstogether as in Example III. Then the entire assemblage is hot rolled.During the rolling procedure, a thin film of molten Al, from the core ofevery Al particle which consists of said metallic Al core in an A1203coating, is smeared onto the surfaces of the Cu particles. This Alreacts with any Cu20 on the surface of the Cu particles, and also, byinterdiliusing with the Cu, which contains some dissolved oxygen as welllas some discrete particles of Cu20, contacts oxygen inside the Cu and-reacts to form sub-micron sized A1203 dispersed particles 68. Removalof the mild steel sheath and cold working then results in dispersoidstrengthened copper.

Example VI-FIG. 6

The process of Example I is repeated except that four bulk copper slabs,each of the dimensions of the total slab indicated in Example II, areenclosed in superposition, snugly within a can of four times the volumeas the can of Example II and with a can Wall thickness correspondinglygreater, e.g. one inch thick. Deoxidation and working under theconditions specified in Example I result in the consolidation of theslabs into a copper sheet or plate 78, whose overall mass is four timesthat of a single slab.

CONCLUSIONS The foregoing disclosure has shown and described variousprocesses involved in enclosing a copper containing assemblage in aniron containing can. The can provides a versatile self-containedenvironment that is useful in effecting de-oxidation to produce oxygenfree copper, consolidated particles and Slabs that are worked tointegrated final products, to win refined copper, on copper whosealloys, from compounds such as copper sulfides and oxides, and copperthat is strengthened by dispersoid particles. The iron of the can eitherparticipates in a reaction therewithin or is shielded from the reactionby its own composition or by ian inner inert coat.

Since certain changes may be made in the foregoing disclosure withoutdeparting from the invention herein involved, it is intended that allmatter described in the foregoing specification or shown in theaccompanying drawings be interpreted in an illustrative and not in alimiting sense.

What is claimed is:

1. A metallurgical process comprising the steps of snugly confining acharge within a can, said charge containing copper as its characteristicingredient, said can containing iron as its characteristic ingredient,and controlling the oxygen content of the system within said can whileheating said can and said charge therein to a temperature within therange of l000 F. to 1800 F.

2. The metallurgical process of claim 1 wherein said charge is a solidslab.

3. The metallurgical process of claim 1 wherein said charge is a powder.

4. The metallurgical process of claim 1 wherein at said temperatureoxygen is removed from said copper by migration from said copper andreaction with said iron.

5. A metallurgical process comprising the steps of snugly confining acharge within a can to provide an assemblage, said charge containingcopper as its characteristic ingredient, said can containing iron as itscharacteristic ingredient, controlling the oxygen content of saidassemblage while heating said can and said charge therein to atemperature within the range of 1000 F. to 1800 F. and mechanicallyworking said assemblage to reduce its thickness in at least onedimension.

6. The metallurgical process of claim 5 wherein said mechanicallyworking is effected by rolling said assemblage to said thickness.

7. A metallurgical process comprising producing an assemblage iby snuglyconfining a copper base charge Within a hermctically controlled ironbase can, heating the assemblage to a temperature within the range of1000 F. to 1800 F., deoxidizing said copper base charge at saidtemperature, rolling said assemblage to provide a monolithic metal blankincluding an intermediate copper base stratum and a pair of outer ironbase strata laminated thereto, and removing said iron base strata fromsaid copper base stratum.

8. The metallurgical process of claim 7 wherein said deoxidizing of saidcopper base charge involves gettering of oxygen from said copper basecharge by said iron base can.

9. The metallurgical process of claim 7 wherein said deoxidizing of saidcopper base charge involves passing hydrogen into said can and reactingsaid hydrogen with the oxygen of said copper base charge.

10. The metallurgical process of claim 7 wherein said charge is at leastone solid slab.

11. The metallurgical process of claim 7 wherein said charge is composedof powder.

12. The metallurgical process of claim 7 wherein said temperature iswithin the range of 1000 F. to l400 F.

13. The metallurgical process of claim 7 wherein said rolling iseffected at a temperature in the range of from 1400 to 1800 F.

14. A metallurgical process comprising producing an intermediateassemblage by snugly confining a copper base charge within ahermetically controlled iron base casing, evacuating said casing throughan opening therein to a pressure below l mm. Hg and hermetically sealingsaid opening, heating said assemblage to a temperature within the rangeof l000 F. to 1800 F. for a sufficient period to enable copper oxide ofsaid copper base charge to decompose into copper and oxygen, migratingthe resulting oxygen through the void separating said copper base chargefrom said iron base casing, reacting said resulting oxygen with saidiron base casing to produce iron oxide at the surface of said iron basecasing, hot rolling said assemblage to provide a monolithic metal blankof intermediate thickness including, as laminations, an inner copperbase stratum and outer iron base strata, removing said outer iron basestrata from said inner copper base stratum and cold rolling said copperbase stratum to nal thickness under temperature conditions at whichoxidation does not occur.

15. The metallurgical process of claim 14 wherein said copper basecharge constitutes at least one slab.

16. The metallurgical process of claim 14 wherein said copper basecharge constitutes a powder.

17. The metallurgical process of claim 14 wherein said iron base can iscomposed of mild steel.

18. The metallurgical process of claim 14 wherein said hot rolling iseffected at a temperature within the range of from 1400 to 1800 F.

19. The metallurgical process of claim 14 wherein said removing saidiron base strata is accomplished by stripplng.

20. The metallurgical process of claim 14 wherein said removing saidiron base strata is accomplished by pickling.

21. A metallurgical process comprising producing an intermediateassemblage by snugly confining a copper base charge within ahermetically controlled iron base casing, simultaneously passinghydrogen through said casing and heating said assemblage to atemperature within the range of l400 F. to 1800" F. for a suflcientperiod to remove oxygen from said charge by reduction with saidhydrogen, hermetically closing said casing, hot rolling said assemblageto provide a monolithic metal blank of intermediate thickness including,as laminations, an inner copper base stratum and outer iron base strata,removing said outer iron base strata from said inner copper base stratumand cold rolling said copper base stratum to nal thickness undertemperature conditions at which oxidation does not occur.

22. The metallurgical process of claim 21 wherein said `copper basecharge constitutes at least one slab.

23. The metallurgical process of claim 21 wherein said copper basecharge constitutes a powder.

24. The metallurgical process of claim 21 wherein said iron base can iscomposed of mild steel.

25. The metallurgical process of claim 21 wherein said hot rolling iseffected at a temperature within the range of from 1400 to l800 F.

26. The metallurgical process of claim 21 wherein said removing saidiron base strata is accomplished by stripp1ng.

27. The metallurgical process of claim 21 wherein said removing saidiron base strata is accomplished by pickling.

References Cited UNITED STATES PATENTS 1,886,615 11/1932 Johnson29-470.9 2,018,725 10/1935 Johnson et al. 29-470.9 2,059,584 1l/l936Johnson 29-470.9 2,290,734 7/ 1942 Brassert 29-4205 2,707,323 5/ 1955Watson 29-470.9

THOMAS H. EAGER, Primary Examiner U.S. Cl. X.R.

